Geeksphone said the Revolution will also be able to run Firefox 2.0, which will soon be available in a beta version that adds an enhanced lock-screen, a universal search feature and copy-and-paste.

Firefox OS is built around applications written in HTML5, and Mozilla Foundation is pitching it as a more open alternative to Android and iOS, better suited to low-end smartphones.

Unlike with other platforms, content purchased by the user is owned by the user, not tied to a particular device, according to Mozilla. Developers are encouraged to distribute apps however they want, and even to build app stores that compete with Mozilla's Firefox Marketplace, it said.

However, the Firefox OS has struggled to compete with Android on sales and performance. Around 390,000 Firefox OS phones shipped last year, according to IDC, a figure it expects to rise to 2.5 million this year.

Geeksphone hopes the freedom to choose between different OSes without voiding the warranty will make up for somewhat underwhelming hardware specifications.

The Revolution is powered by an Intel Z2560 Atom dual-core processor running at 1.6GHz, with a 4.7-inch, 960 by 540 pixel screen. It has 1GB of RAM and 4GB of integrated storage, which can be expanded using a microSD card. The phone also has an 8 megapixel camera and a 2,000 mAh battery.